diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/ArtifactFunction.java b/src/main/java/com/google/devtools/build/lib/skyframe/ArtifactFunction.java
index fb64daef55db96..418ead4630750e 100644
--- a/src/main/java/com/google/devtools/build/lib/skyframe/ArtifactFunction.java
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/ArtifactFunction.java
@@ -437,8 +437,9 @@ private static final class ArtifactFunctionException extends SkyFunctionExceptio
 
   private static String constructErrorMessage(Artifact artifact, String error) {
     Label ownerLabel = artifact.getOwner();
-    if (ownerLabel == null) {
-      // Discovered inputs may not have an owner.
+    if (ownerLabel == null || ownerLabel.getName().equals(".")) {
+      // Discovered inputs may not have an owner. Directory source artifacts may be owned by a label
+      // ':.' which will crash toPathFragment below.
       return String.format("%s '%s'", error, artifact.getExecPathString());
     } else if (ownerLabel.toPathFragment().equals(artifact.getExecPath())) {
       // No additional useful information from path.